Smoking influence on early and late fetal growth.

Objectives: Smoking during pregnancy is a leading and modifiable risk factor for fetal growth restriction (FGR) and low birthweight (<10th centile). We studied the effects of smoking in the development of early and late FGR or low birthweight, as well as in uteroplacental and fetoplacental hemodynamics of growth-restricted fetuses.

Methods: Retrospective cohort study of 5,537 consecutive singleton pregnancies delivered at ≤34 + 0 ("early delivery" group, n=95) and >34 + 0 ("late delivery" group, n=5,442) weeks of gestation.